Cycloalkylthio(electron-withdrawing group substituted)aniline compounds

ABSTRACT

Cycloalkylthioanilines having at least two electron-withdrawing groups on a phenyl ring are efficient vulcanization retarders. The compounds are prepared by the reaction of an aniline compound having at least two electron-withdrawing groups on a phenyl ring with a cycloalkanesulfenyl chloride.

This is a division of application Ser. No. 367,643, filed June 6, 1973,now U.S. Pat. No. 3,895,060.

BACKGROUND OF THE INVENTION

Unsaturated polymers are admixed with compounding and cure ingredients,processed and formed into shapes, and cure to yield finished products.If cure starts during processing and forming operations, the polymermixture (stock) gets tough and hard to work, and often is discarded.This toughening phenomenon, known as scorching, is caused by prematureactivation of the vulcanization accelerator(s). Vulcanization retardersare used to delay the action of the accelerators. However, many of theolder known types of retarders such as salicyclic acid, benzoic acid,and N-nitrosodiphenylamine are only marginally effective when used withthe so-called fast-acting accelerators such as 2-mercaptobenzothiazoleand the like. The problem of scorching is even more serious whenamine-based antioxidants and antiozonants or high pH carbon blacks, allof which make stocks more scorchy, are employed. New compounds areneeded to impart safety to scorchy stocks. Compounds as vulcanizationretarders are disclosed in U.S. Pat. Nos. 3,513,139; 3,539,538;3,546,185; 3,562,225; 3,586,696; 3,637,844; and 3,640,976.

SUMMARY OF THE INVENTION

Cycloalkylthioaniline compounds of the formula ##SPC1##

Wherein X is an electron-withdrawing group and n is 2 to 4; R ishydrogen, an alkyl radical containing 1 to about 8 carbon atoms, an arylgroup containing 6 to about 14 carbon atoms which can containelectron-withdrawing groups, or --SR'; and R' is a cycloalkyl radicalcontaining 4 to 8 carbon atoms in the ring, are highly effectivevulcanization retarders for sulfur-vulcanizable polymers containingsulfur and accelerator compounds.

DETAILED DESCRIPTION

The cycloalkylthioaniline compounds have the formula ##SPC2##

Wherein X is an electron-withdrawing group and n is 2 to 4; R ishydrogen, an alkyl radical containing 1 to about 8 carbon atoms, an arylgroup containing 6 to about 14 carbon atoms which can containelectron-withdrawing groups, or --Sr'; and R' is a cycloalkyl radicalcontaining 4 to 8 carbon atoms in the ring. The cycloalkyl radical canbe further substituted with 1 to 4 carbon atom alkyl radicals. Examplesof electron-withdrawing groups are --Cl, --Br, --I, --F, --SO₂ R_(a),--NO₂, and --COOR_(a) where R_(a) is an alkyl radical containing 1 to 18carbon atoms.

Examples of the cycloalkylthioaniline compounds are:N-cyclobutylthio-2,4-dichloroaniline,N-cyclobutylthio-2,4-dibromoaniline,N-cyclobutylthio-2,4-dichloro-6-nitroaniline,N-cyclobutylthio-2,4-di(ethylcarbooxy)aniline,N-cyclobutylthio-2,4-dinitroaniline,N-cyclobutylthio-2-bromo-4-nitroaniline,N-cyclobutylthio-N-methyl-2,4-dinitroaniline,N,N-di(cyclobutylthio)-3,5-dinitroaniline,N-cyclopentylthio-N-phenyl-2,4-dibromoaniline,N-cyclopentylthio-2,4-dichloroaniline,N-cyclopentylthio-2,6-dichloro-4-nitroaniline,N-cyclopentylthio-N-ethyl-2,4-dichloroaniline,N-cyclopentylthio-2,6-dinitroaniline,N-cyclopentylthio-2-bromo-4,6-dinitroaniline,N-cyclopentylthio-2,4-di(methylsulfonyl)aniline,N-cyclopentylthio-2,4,5-trichloroaniline,N-cyclohexylthio2,4-dibutylcarbooxyaniline,N-cyclohexylthio-2,4-dichloroaniline,N-cyclohexylthio-2-chloro-5-nitroaniline,N-cyclohexylthio-N-propyl-2,6-dichloroaniline,N-cyclohexylthio-N-(2,4-dinitrophenyl)-2,4-dinitroaniline,N-cyclohexylthio-2,4-difluoroaniline,N-cyclohexlthio-2,4-di(ethylsulfonyl)aniline,N-cyclohexylthio-2,4-dinitroaniline,N-cyclohexylthio-3-iodo-5-nitroaniline,N-cyclohexylthio-N-methyl-2,4-dinitroaniline,N-cyclohexylthio-2,6-diiodo-4-nitroaniline,N-cyclohexylthio-N-phenyl-3,4-dichloroaniline,N-(4-methylcyclohexylthio)-2,4-dinitroaniline,N-(3,5-diethylcyclohexylthio)-3,4-dichloroaniline,N-cyclohexylthio-2,4,6-tribromoaniline,N,N-di(cyclohexylthio)-2,4-dinitroaniline,N-cycloheptylthio-2,5-dibromoaniline,N-cycloheptylthio-2,3,5,6-tetrafluoroaniline,N-cycloheptylthio-N-tolyl-2,4-di(ethylsulfonyl)aniline,N-cycloheptylthio-4-fluoro-3-nitroaniline,N-cycloheptylthio-2,4-dinitroaniline,N-cycloheptylthio-N-ethyl-2,4-dinitroaniline,N-cycloheptylthio-2,3,4,5-tetrachloroaniline,N-cycloheptylthio-3,5-dichloroaniline,N-cycloheptylthio-2,5-dichloroaniline,N-cycloheptylthio-2-chloro-5-nitroaniline,N-cyclooctylthio-2,4-dinitroaniline,N-cyclooctylthio-2,4-dichloroaniline,N-cyclooctylthio-2-fluoro-5-nitroaniline.

More preferred, the cycloalkylthioaniline compound has the formula##SPC3##

wherein X₁ is selected from the group consisting of --Cl, --NO₂, and--COOR'_(a) where R'_(a) is an alkyl radical containing 1 to 8 carbonatoms; R₁ is hydrogen, a phenyl radical containing two X₁ groups, or--SR'₁ ; and R'₁ is a cycloalkyl radical containing 5 to 7 carbon atomsin the ring. X₁ is usually located at the 2,3; 2,4; 2,5; 2,6; 3,4; or3,5 positions on the phenyl ring.

Examples of the more preferred compounds are:N-cyclopentylthio-2,3-dichloroaniline,N-cyclopentylthio-2,4-dichloroaniline,N-cyclopentylthio-2,6-dichloroaniline,N-cyclopentylthio-2,4-dinitroaniline,N-cyclopentylthio-N-(3,4-dichlorophenyl)-3,4-dichloroaniline,N-cyclopentylthio-2-chloro-5-nitroaniline,N,N-di(cyclopentylthio)-2,4-dinitroaniline,N-cyclohexylthio-3,4-dichloroaniline, N-cyclohexyl-2,6-dinitroaniline,N-cyclohexylthio-2,4-di(ethylcarbooxy)aniline,N-cyclohexylthio-N-(2,4-dichlorophenyl)-2,4-dichloroaniline,N-cyclohexylthio-3,5-dinitroaniline,N-cyclohexylthio-2,4-dinitroaniline,N-cyclohexylthio-4-chloro-2-nitroaniline,N-cyclohexylthio-2,4-dinitroaniline,N,N-di(cyclohexylthio)-2,4-dinitroaniline,N-cycloheptylthio-2,4-dichloroaniline,N-cycloheptylthio-2-chloro-5-nitroaniline,N-cycloheptylthio-3,4-dichloroaniline,N-cycloheptylthio-N-(2,4-dinitrophenyl)-2,4-dinitroaniline,N-cycloheptylthio-2,4-dinitroaniline, and the like.

Even more preferred, the compounds contain dinitro- or dichloroanilinegroups; i.e., where X₁ is --NO₂ or --Cl, R₁ is hydrogen and R₁ ' is acycloalkyl radical containing 5 to 7 carbon atoms in the ring. Examplesof the compounds are: N-cyclopentylthio-2,4-dichloroaniline,N-cyclopentylthio-2,6-dichloroaniline,N-cyclopentylthio-2,4-dinitroaniline,N-cyclohexylthio-3,4-dichloroaniline,N-cyclohexylthio-2,6-dinitroaniline,N-cyclohexylthio-3,5-dinitroaniline,N-cyclohexylthio-2,4-dinitroaniline,N-cycloheptylthio-2,4-dichloroaniline,N-cycloheptylthio-2,3-dichloroaniline,N-cycloheptylthio-2,4-dinitroaniline, and the like.

The compounds are prepared by the reaction of a cycloalkanesulfenylchloride with aniline compounds. The reaction follows that employed byBehrorouz et al., Journal of Organic Chemistry, Vol. 34, Page 51 (1969).The cycloalkanesulfenyl chloride is prepared by reacting acycloalkylthiol of the formula H--S--R', where R' is defined as above,with chlorine gas. This reaction is usually conducted in a solvent suchas hexane, carbon tetrachloride, ethylidene trichloride, and the like,at a temperature from about -20°C. to about 30°C.

The cycloalkanesulfenyl chloride is reacted with an aniline of theformula ##SPC4##

wherein X_(n) and R are defined as above. The reaction temperatureranges from about -10°C. to about 60°C. Solvents for the reaction arehexane, heptane, carbon tetrachloride, ethylidene trichloride, benzene,chlorobenzene, tetrahydrofuran, dioxane, dimethylformamide, and thelike. A mixture of two solvents can be employed. A particularly usefulcombination is to employ a mixture of tetrahydrofuran ordimethylformamide along with an alkyl or halogenated alkyl hydrocarbon.

The reaction can be catalyzed by tertiary amines such as triethylamineand the like, or by an organic lithium compound such as n-butyl lithium.Reaction time is from about 1 to 4 hours.

The cycloalkanesulfenyl chloride and the aniline compound are used inthe reaction at about 1 to 4 moles of cycloalkanesulfenyl chloride permole of aniline compound. It is not necessary to use over 4 moles of thechloride to achieve the instant compounds. If in the aniline compound Ris hydrogen, the cycloalkanesulfenyl chloride can react with bothhydrogens of the aniline compound to prepare a di(cycloalkylthio)aniline compound.

The cycloalkylthioaniline compound can be isolated from the reactionsolution by drying down or coagulation using water followed byfiltration and drying. The compound can be purified by washing withwater and/or recrystallization from hexane. The cycloalkylthioanilinescan be characterized by their Infra-red (IR) and nuclear magneticresonance (NMR) spectra, and/or by carbon, hydrogen, nitrogen, andsulfur analysis.

The cycloalkylthioaniline compounds are used in a range from about 0.05part to about 5 parts by weight per 100 parts by weight of polymer. Morepreferredly, they are used in from about 0.1 part to about 3 parts byweight. The compounds are effective retarders, often delaying the onsetof cure 100% or more when used at a level of from about 1 part byweight. They are useful with a broad range of sulfur- and nitrogen-basedaccelerator compounds. Examples of these accelerators are the metalsalts of dialkyl and diaryldithiocarbamates such as zinc and leaddimethyldithiocarbamate, zinc, bismuth, cadmium, selenium, and telluriumdiethyldithiocarbamate, sodium dibutyldithiocarbamate, zincdibenzyldithiocarbamate, and the like, andbis-(dimethylthiocarbamyl)sulfide, N-pentamethyleneammoniumN-pentamethylenedithiocarbamate, and the like; benzothiazoles andbenzothiazole-sulfenamides such as 2-mercaptobenzothiazole and the zincsalt thereof, 2-(2,6-dimethyl-4-morpholinothio)benzothiazole,2-benzothiazole-4-morpholinyl disulfide, 2,2'-benzothiazyl disulfide,N-diisopropyl-2-mercaptobenzothiazole sulfenamide,N-t-butyl-2-benzothiazole sulfenamide, N-cyclohexyl-2-benzothiazolesulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, and the like;thiuram sulfides such as tetramethylthiuram mono- and disulfide,tetraethylthiuram disulfide, tetrabutylthiuram monosulfide, and thelike; thioureas such as ethylenethiourea, trimethylthiourea,N,N'-diethylthiourea, N,N' -dibutylthiourea, N,N'-diphenylthiourea, andthe like; morpholines such as 4,4'-dithiomorpholine; polyamines such astriethylene diamine, hexamethylene tetraamine, tricretonylidenetetraamine, and the like; amine and aldehyde condensation products suchas acetaldehyde-ammonia, butyraldehyde-butylamine,butyraldehyde-aniline, heptaldehyde-aniline,ethylchloride-formaldehyde-ammonia, and the like; imidazolines such as2-mercaptoimidaxoline; and guanidines such as diphenylguanidine,di-ortho-tolylguanidine, and the like.

The accelerators may be used alone or in combination with each other.They are used in levels from about 0.05 to about 7 parts by weighttotal, and more preferably from about 0.2 part to about 5 parts byweight per 100 parts by weight of polymer. Elemental sulfur or sulfurdonors such as dipentamethylenethiuram hexasulfide are employed with thevulcanization accelerators in levels from about 0.1 to about 10 parts byweight.

The cycloalkylthioaniline vulcanization retarders are used to delay thecure of sulfur vulcanizable polymers. These polymers have an olefinic(>C=C<) content of from about 0.1 to about 45% by weight based upon thetotal weight of the polymer. The olefinic unsaturation can be in thepolymer backbone or can be present as side-chain unsaturation. Thesepolymers are usually highly unsaturated rubbers containing at least 50%and up to 100% by weight of a conjugated diene monomer containing 4 toabout 8 carbon atoms, and up to about 50% by weight of copolymerizablevinylidene monomers having a terminal vinylidene (CH₂ =C<) group.Examples of the conjugated diene monomers are butadiene, isoprene,chloroprene, 2-isopropyl-1,3-butadiene, 1,3-pentadiene, and the like.More preferred are the conjugated dienes containing 4 to about 6 carbonatoms such as butadiene, chloroprene, and isoprene.

Examples of copolymerizable vinylidene monomers containing a terminalvinylidene group are (a) monoolefins containing 2 to about 8 carbonatoms; (b) vinyl aromatics such as styrene, α-methyl styrene, vinyltoluene, chlorostyrene, and the like; (c) vinyl nitriles such asacrylonitrile, methacrylonitrile, and the like; (d) vinyl and allylesters such as vinyl acetate, vinyl propionate, allyl acetate, and thelike; (e) vinyl and allyl ethers such as vinyl methyl ether, allylmethyl ether, and the like; (f) divinyls and diacrylates such asdivinylbenzene, divinyl ether, diethylene glycol diacrylate, and thelike; and (g) acrylates of the formula ##EQU1## wherein R' is --H, --CH₃or --C₂ H₅, and R" is an alkyl radical containing 1 to 18 carbon atomsor an alkoxyalkyl, an alkylthioalkyl, or cyanoalkyl radical containing 2to about 12 carbon atoms. Examples of such acrylates are ethyl acrylate,butyl acrylate, octadecyl acrylate, methoxyethyl acrylate, butoxyethylacrylate, hexylthioethyl acrylate, β-cyanoethyl acrylate, cyanooctylacrylate, methyl methacrylate, octyl methacrylate, ethyl ethacrylate,and the like.

The highly unsaturated rubbers include natural rubber, the generalpurpose synthetic rubbers, and specialty rubbers. Examples of the highlyunsaturated diene rubbers are natural rubber, polyisoprenes,polybutadienes, poly(butadiene-styrene) rubbers, poly(isoprene-styrene)rubbers, polychloroprenes, poly(butadiene-acrylonitrile) rubbers,poly(isoprene-acrylonitrile) rubbers, polypentenamer rubbers, and thelike.

Other useful sulfur vulcanizable polymers containing from about 0.1 toabout 20% by weight of olefinic unsaturation are readily employed.Examples of such are isoprene-isobutylene (Butyl) rubbers;ethylene-propylene-diene polymers (EPDM) containing from about 0.5 toabout 20% by weight of a diene monomer where the diene is conjugated asin butadiene, 1,3-pentadiene, and the like; non-conjugated as in1,4-pentadiene, 1,4-hexadiene, and the like; cyclic dienes as incyclopentadiene, dicyclopentadiene, and the like; an alkenyl norbornenesuch as 5-ethylidene-2-norbornene, 2-isopropenyl-5-norbornene, and thelike; and others such as 3-ethylbicyclonondiene and3-methyltricyclo-(5,2,1,0²,6)-3,8-decadiene; and polyether terpolymerscontaining about 0.5 to about 20% by weight of allyl glycidyl ether orglycidyl acrylate or methacrylate.

The cycloalkylthioaniline retarders can be used with a full range ofcompounding ingredients. This includes activators such as metal oxideslike zinc and magnesium oxide, lead monoxide, fatty acids such asstearic and lauric acid, and salts thereof such as cadmium, zinc andcopper stearate and lead oleate; fillers such as the carbon blacks,calcium and magnesium carbonates, calcium and barium sulfates, aluminumsilicates, phenol-formaldehyde and polystyrene resins, asbestos, and thelike; plasticizers and extenders such as dialkyl and diaryl organicacids like diisooctyl, and dibenzyl oleates, stearates, and phthalates,ASTM type 2 petroleum oils, ASTM D2226 aromatic, naphthalenic andparaffinic oils, and the like; antioxidants, antiozonants, andstabilizers such as di-β-naphthyl-p-phenylenediamine,phenyl-β-naphthylamine, dioctyl-p-phenylenediamine,N-1,3-dimethylbutyl-N-phenyl-p-phenylenediamine, 4-isopropylaminodiphenylamine, 2,6-di-t-butyl paracresol,2,2'-methylenebis-(4-ethyl-6-t-butyl phenol),2,2'-thiobis-(4-methyl-6-t-butyl phenol),bisphenol-2,2'-methylenebis-6-t-butyl-4-ethylphenol,4,4'-butylidenebis-(6-t-butyl-m-cresol),2-(4-hydroxy-3,5-t-butylaniline)-4,6-bis(octylthio)-1,4,5-triazine,hexahydro-1,3,5-tris-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionyl-s-triazine,tris-(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate,tetrakismethylene-3-(3',5'-di-t-butyl-4-hydroxyphenyl)propionatemethane, distearyl thiodipropionate, dilauryl thiodipropionate,tri(nonylatedphenyl)phosphite, and the like; and other ingredients suchas pigments, tackifiers, flame retardants, fungicides, and the like.

The vulcanization retarders, accelerators, sulfur, and other compoundingingredients are admixed with the polymer using conventional equipmentsuch as two-roll mills and internal mixing equipment such as banburys,extruders, and Brabender mixers. Standard mixing and addition techniquesare employed.

The effectiveness of the retarders can be measured as the increase inscorch time that the compound produces in the stock. Scorch time can bedetermined by various methods. A standard method is ASTM Procedure D1646 wherein, using a Mooney Viscometer with a large rotor, a T₅ valueis determined. This value is the time in minutes for a compoundedpolymer stock heated at a set temperature to reach a minimum viscosityvalue and then to rise 5 units over this value. Scorch time can also bedetermined by using a Monsanto Rheometer and measuring T₂, the time inminutes for a stock to advance 2 chart units over minimum. Anothermethod is to use the B.F.G. Cone Curometer described in U.S. Pat. No.3,494,172. The stock is placed in a conical cavity and then a rambrought down and oscillated. The resistance to the ram's movementexerted by the stock is displayed as torque versus time (at a settemperature). The time measured is T_(s), 2 or T_(s), 3, which is thetime in minutes for the torque to rise 2 (or 3) inch-pounds over theminimum torque value. A longer time of T_(s), 2 indicates increasedscorch safety.

Once the stock starts to cure, cure rates using thecycloalkylthioaniline retarders are about as fast as those obtainedwithout using the retarders. The stocks are cured at a temperature rangefrom about 250° to about 450°F. The temperature chosen is usuallydetermined by the type of polymer used and the mixing equipmentemployed.

The cycloalkylthioanilines have many practical uses. Their use allowsthe use of fast-curing accelerators in standard or ordinary processingprocedures where otherwise the accelerators would be too scorchy. Bydelaying the onset of cure, higher processing temperatures may beemployed, thereby increasing product output. Stocks which are marginallyscorchy can be made less scorchy resulting in less waste. Also, storagecapacity of stocks can be greatly improved with the addition of thecompounds. Further advantages will become apparent to those skilled inthe art.

The following examples are set forth to illustrate specific embodimentsof the invention. Ingredients used are given in parts by weight unlessotherwise indicated. Tensile, modulus, and elongation were measuredfollowing ASTM D 412.

EXAMPLE I Preparation of Cyclohexanesulfenyl chloride

116.2 grams of cyclohexylmercaptan was placed in a reactor vessel with750 milliliters of heptane. The solution was stirred and cooled to -5°to -10°C. Chlorine gas was then bubbled through the solution for 129minutes at a rate of 35.0 grams per hour (70 grams total of Cl₂). Thennitrogen gas was bubbled through the solution until no hydrogen chloridewas detected in the exit gas (about 4 hours). The solution was stored at0°C. for future use.

Preparation of N-cyclohexylthio-2,4-dinitroaniline

Procedure A

2,4-dinitroaniline, 45.8 grams, was placed in a reactor vessel with 450milliliters of dimethylformamide and 75 grams of triethylamine as acatalyst. 385 milliliters of the above solution of cyclohexanesulfenylchloride in heptane was then added at a rate of about 7 milliliters perminute. Temperature at the start of the addition was 23°C. and at theend 34°C. After the addition, about 1 hour, the mixture was stirredovernight (about 16 hours) at room temperature. The mixture was thenfiltered to remove a water-soluble precipitate. The filtrate wasseparated and the dimethylformamide phase was poured into ice water. Abrown solid formed which was filtered out. The solid was mixed withtrichloromethane and water. A solid forming at the interface of thephases was filtered out. The trichloromethane phase was concentrated byevaporating off the solvent, yielding a dark yellow liquid. Hexane wasadded to the liquid and a yellow-brown solid formed, which was laterrecrystallized from hexane to yield a solid having a melting point of86°-88°C. 6.2 grams of compound was obtained. The compound wasidentified through its NMR spectra asN-cyclohexylthio-2,4-dinitroaniline. The calculated carbon, nitrogen,and hydrogen weight percents were 48.3%, 14.0%, and 5.6% respectively.The values found were 48.2% carbon, 14.1% nitrogen, and 5.2% hydrogen.

Procedure B

Tetrahydrofuran, 250 milliliters, and 22.9 grams of 2,4-dinitroanilinewas placed in a reactor vessel and stirred at room temperature. Nitrogengas was then introduced to evacuate the vessel of air. 100 millilitersof a solution of 23.1% by weight n-butyl lithium in hexane (0.25 mole ofn-butyl lithium) was slowly added. Temperature rose throughout theaddition to 85°C. The solution was then cooled to 30°C. and acyclohexanesulfenyl chloride solution (0.25 mole) prepared as above wasadded at 14 milliliters per minute. The mixture was stirred overnight.The reaction mixture was filtered to remove a water-soluble solid, andthe filtrate concentrated to about 300 milliliters by evaporating offtetrahydrofuran. A dark red-brown solid precipitated out and wasseparated out by filtration. The solid was washed with isopropanol,which yielded a yellow solid, and then was washed with water. The yellowsolid was recrystallized from hexane to yield 8.3 grams of a yellowproduct which was identified by its NMR spectrum to beN-cyclohexylthio-2,4-dinitroaniline.

Using the same procedures, and employing other electron-withdrawinggroup substituted anilines for the 2,4-dinitroaniline employed above,yields many other cycloalkylthio-(electron-withdrawing groupsubstituted) aniline compounds which are useful as vulcanizationretarders. Procedure B, using the organo-lithium catalyst, works betterto prepare cycloalkylthioaniline compounds substituted with halogengroups, especially with chlorine groups.

EXAMPLE II

The N-cyclohexylthio-2,4-dinitroaniline prepared in Example I wasevaluated as a vulcanization retarder in a cure of SBR rubber. The SBRrubber has a composition of 23.5% by weight of styrene and 76.5% byweight of butadiene and a Mooney value (ML-4 at 212°F.) of about 50. Therecipe used and data obtained is as follows:

                     1        2                                                   ______________________________________                                        SBR                100        100                                             HAF black          50         50                                              Stearic acid       3          3                                               Zinc oxide         5          5                                               BBTS.sup.1         1          1                                               Sulfur             2          2                                               CHTA.sup.2         --         0.5                                             Monsanto rheometer at 284°F.                                            T.sub.2, minutes  15.2       20.6                                             Δtorque, inch-pounds                                                                      75.0       73.5                                            Cured at 320°F.                                                         cure time, minutes                                                                              14         19                                              300% modulus, psi  2250       2520                                            Tensile, psi       2650       3450                                            Elongation, percent                                                                              350        370                                             ______________________________________                                         .sup.1 N-t-butyl-2-benzothiazolesulfenamide                                   .sup.2 N-cyclohexylthio-2,4-dinitroaniline                               

The samples show that the N-cyclohexylthio-2,4-dinitroanilineeffectively delayed the onset of cure in the SBR polymer. The curedproperties of Sample 2 are even better than those of Sample 1 whichcontained no aniline compound.

EXAMPLE III

The N-cyclohexylthio-2,4-dinitroaniline compound was also evaluated as avulcanization retarder in the cure of a poly(butadiene-acrylonitrile)rubber, an NBR rubber. The NBR has an acrylonitrile content of 33% byweight and a butadiene content of 67%, and a Mooney value of 80 (ML-4 at212°F.). The recipes used and the data obtained are as follows:

                     1        2                                                   ______________________________________                                        NBR                100        100                                             FEF black          40         40                                              Stearic acid       1          1                                               Zinc oxide         5          5                                               PBNA.sup.1         1          1                                               MBTS.sup.2         1          1                                               Sulfur             1.5        1.5                                             CHTA.sup.3         --         0.5                                             Monsanto rheometer at 284°F.                                            T.sub.2, minutes  8.2        11.0                                             Δtorque, inch-pounds                                                                      82         73                                              Cured at 302°F.                                                         cure time, minutes                                                                              17         21                                              300% modulus, psi  2070       1890                                            Tensile, psi       3130       3240                                            Elongation, percent                                                                              440        470                                             ______________________________________                                          .sup.1 N-phenyl-β-naphthylamine                                          .sup.2 2,2'-dibenzothiazyl disulfide                                          .sup.3 N-cyclohexylthio-2,4-dinitroaniline                              

The N-cyclohexylthio-2,4-dinitroaniline effectively delayed the onset ofcure of the NBR polymer. Sample 2, containing the aniline compound, hadphysical properties as good as or better than Sample 1.

EXAMPLE IV

Natural rubber cures very fast in the presence of benzothiazoleaccelerators. N-cyclohexylthio-2,4-dinitroaniline was evaluated as avulcanization retarder in pale crepe Natural Rubber. The recipe employedwas: 100 parts by weight Natural rubber, 50 parts HAF carbon black, 3parts stearic acid, 5 parts zinc oxide, 1 part (OBTS) N-oxydiethylenebenzothiazole-2-sulfenamide, and 2.5 parts by weight of sulfur. Thecomposition had a scorch time, T₂ of 8.9 minutes using a Monsantorheometer at 284°F. When 1.0 part by weight ofN-cyclohexylthio-2,4-dinitroaniline was added to the above recipe, theT₂ scorch time was 21.7 minutes, indicating a 144% increase in scorchsafety. A commercial vulcanization retarder, Santogard PVI(N-cyclohexylthiophthalimide), was also evaluated at 1.0 part by weight.The PVI yielded comparable scorch safety, but three months after curethe stock showed medium to heavy bloom on the surface. In contrast, thestock containing the aniline compound showed only slight bloom after 3months.

EXAMPLE V

A cycloalkylthio (electron-withdrawing group substituted) anilinecompound of the present invention was compared with a similar compounddisclosed in the art. In U.S. Pat. No. 3,513,139, column 8, lines 20 to26, the compound N-(phenylthio)aniline showed a 72% increase in scorchdelay when used at 1.0 part by weight in a Natural rubber recipe. Theexample was repeated except for the use of 1.0 part by weight ofN-cyclohexylthio-2,4-dinitroaniline in place of the N-phenylthioaniline.The recipe used was: 100 parts by weight natural rubber, 50 parts HAFcarbon black, 5 parts zinc oxide, 3 parts stearic acid, 10 partssoftener, 3.0 parts Santoflex 77(N,N'-bis(1,4-dimethylphenyl)-p-phenylenediamine), 0.5 part SantocureMOR (2-morpholinothiobenzothiazole), 0.5 part of sulfur, and 1.0 part byweight of N-cyclohexylthio-2,4-dinitroaniline. The composition was thenevaluated for its scorch time at various times and temperatures. Theconditions and data obtained are as follows:

                 Without With      Percent                                                     compound                                                                              compound  increase                                       ______________________________________                                        Mooney scorch at 250°F.                                                 T.sub.5, minutes                                                                            21.0      59.0      181                                        Mooney scorch at 275°F.                                                 T.sub.5, minutes                                                                            8.9       22.7      155                                        Monsanto rheometer at                                                         291°F.                                                                  T.sub.2, minutes                                                                            4.0       9.4       135                                        ______________________________________                                    

In all three instances, the percent increase in scorch safety was about2 to 2.5 times as great as the scorch safety obtained using the knownN-phenylthioaniline compound.

I claim:
 1. A composition comprising (a) a sulfur-vulcanizable polymerhaving an olefinic unsaturation content of from about 0.1 to about 45%by weight of the polymer, (b) sulfur or a sulfur donor, (c) avulcanization accelerator, and (d) a cycloalkylthio aniline of theformula ##SPC5##wherein X is an electron-withdrawing group selected fromthe group consisting of --Cl, --Br, --I, --F, --SO₂ R_(a), --NO₂, and--COOR_(a) wherein R_(a) is an alkyl radical containing 1 to 18 carbonatoms, n is an integer from 2 to 4, R is selected from the groupconsisting of hydrogen, an alkyl radical containing 1 to about 8 carbonatoms, a phenyl radical which can be substituted with --X_(n) groups,and --SR', and R' is a cycloalkyl radical containing 4 to 8 carbon atomsin the ring.
 2. A composition of claim 1 where in (d) X is selected fromthe group consisting of --Cl, --NO₂, and --COOR_(a) ' where R_(a) ' isan alkyl radical containing 1 to 8 carbon atoms, R is hydrogen, phenyl,or an alkyl radical containing 1 to about 8 carbon atoms, n is 2, and R'is a cycloalkyl radical containing 5 to 7 carbon atoms in the ring.
 3. Acomposition of claim 2 where in (a) the sulfur-vulcanizable polymer isselected from the group consisting of natural rubber, polyisoprenes,polybutadienes, poly(bitadienestyrene) rubbers, polychloroprenes,poly(butadiene-acrylonitrile) rubbers, poly(isoprene-acrylonitrile)rubbers, polypentenamer rubbers, isoprene-isobutylene rubbers, andethylene-propylenediene rubbers.
 4. A composition of claim 3 where in(b) the vulcanization accelerator is selected from the group consistingof N-t-butyl-2-benzothiazolesulfenamide, 2,2'-dibenzothiazyl disulfide,N-oxydiethylene benzothiazole sulfenamide, and2-(4-morpholinothio)benzothiazole.
 5. A composition of claim 4 wherein(d) is N-cyclohexylthio-2,4-dinitroaniline.
 6. A composition consistingessentially of (1) a vulcanization accelerator, (2) a cycloalkylthioaniline of the formula ##SPC6##wherein X is an electro-withdrawing groupselected from the group consisting of --Cl, --Br, --I, --F, --SO₂ R_(a),--NO₂ and --COOR_(a), wherein R_(a) is an alkyl radical containing 1 to18 carbon atoms, n is an integer from 2 to 4, R is selected from thegroup consisting of hydrogen, an alkyl radical containing 1 to about 8carbon atoms, a phenyl radical which can be substituted with --X_(n)groups, and -SR', and R' is a cycloalkyl radical containing 4 to 8carbon atoms in the ring, and (3) sulfur or a sulfur donor.
 7. Acomposition of claim 6 where in (2) X is selected from the groupconsisting of --Cl, --NO₂, and --COOR_(a) ' where R_(a) is an alkylradical containing 1 to 8 carbon atoms, R is hydrogen, phenyl, or analkyl radical containing 1 to about 8 carbon atoms, n is 2, and R' is acycloalkyl radical containing 5 to 7 carbon atoms in the ring.
 8. Acomposition of claim 7 wherein (2) isN-cyclohexylthio-2,4-dinitroaniline.
 9. A composition consistingessentially of (1) a vulcanizable accelerator and (2) a cycloalkylthioaniline of the formula ##SPC7##wherein X is an electron-withdrawinggroup selected from the group consisting of --Cl, --Br, --I, --F, --SO₂R_(a), --NO₂ and --COOR_(a) wherein R_(a) is an alkyl radical containing1 to 18 carbon atoms, n is an integer from 2 to 4, R is selected fromthe group consisting of hydrogen, an alkyl radical containing 1 to about8 carbon atoms, a phenyl radical which can be substituted with --X_(n)groups, and -SR', and R' is a cycloalkyl radical containing 4 to 8carbon atoms in the ring.
 10. A composition of claim 9 where in (2) X isselected from the group consisting of --Cl, --NO₂, and --COOR_(a) 'where R_(a) ' is an alkyl radical containing 1 to 8 carbon atoms, R ishydrogen, phenyl, or an alkyl radical containing 1 to about 8 carbonatoms, n is 2, and R' is a cycloalkyl radical containing 5 to 7 carbonatoms in the ring.
 11. A composition of claim 10 where in (1) isselected from the group consisting of N-t-butyl-2-benzothiazolesulfenamide, 2,2'-dibenzothiazyl disulfide, N-oxidiethylenebenzothiazole sulfenamide, and 2-(4-morpholinothio)benzothiazole and (2)is N-cyclohexylthio-2,4-dinitroaniline.